摘要:

AbstractThe research reported in the article focuses on modifying glass fiber surfaces with polyacrylic acid (PAA) compounds. E‐glass fibers were treated with aqueous polyacrylic acid solution. Polyacrylic acid exchanges its protons with the ions present in the glass surface. Hydrolyzed metal cations may form salt complexes with the dissociated polyacrylic acid. Angular dependent electron spectroscopy for chemical analysis (ESCA) demonstrated that the atomic concentrations of aluminum and calcium in the glass fiber surface were constant throughout the analyzed interval. The cation exchange property of glass fiber was studied using direct current plasma (DCP), which showed that both calcium and aluminum ions were extracted by low concentration polycrylic acid solutions. ESCA studies of were extracted by low concentrationb polyacrylic acid solutions. ESCA studies of the PAA‐treated glass fiber showed that the amount of PAA of the glass surface increases with increased acid concentration. A broadened and shifted ESCA peak of the carbon (0CO) indicates the formation of salt complexes between the polyacrylic acid and metal ions on the glass surface. Polyacrylie acid was modified by an esterification reaction with glycidyl acrylate (GA) in aqueous solution in order to insert organofuctional groups into the PA

ISSN:0272-8397    

DOI:10.1002/pc.750140102

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractBioabsorbable composites have been fabricated, consisting of poly (glycolic acid) surgical mesh embedded in free radically crosslinked poly (D, Iactide‐co‐8‐caprolactone) fumarate‐ or poly(D, Iactide‐co‐‐glycolic acid) fumarate‐based matrices. Styrene and methyl methacrlate were investigated as hydrophobic comonomers and were found to significantly improve the degree of crosslinking, tensile strength and retention of physical properties during the initial stages of degradation particularly styrene. Hydrolytic degradation studies showed that the neat poly(D, L‐lactide‐co‐8caprolactone) fumarate matrix dwas excessively hydrophilic, failing after 10 days of immersion; a matrix modified with 25 wt% styrene underwent a steady, nearly linear loss in mass over a period of 35 days without fragmentation. A composite based on neat poly (D, L‐lactide‐co‐8‐caprolactone) fumarate displayed a tensile strength of 37 Mpa and modulus of 107 Mpa; addition of 25 wt% styrene yielded tensile strength and modulus of 64 Mpa and 689 Mpa, respectively. A silane coupling agent was shown to dramatically improve the fiber‐matrix interfacial adhesion; tensile strength of a poly(D, L‐lactide‐co‐glycolic acid) fumarate compsite was increase from 84 to 92 MPa upon fiber pretreatment. Improved adhesion was also demonstrated using SEM. Bioabsorbable composites are rigid at biological temperatures, but some can be custom formed at elevated temperatures, which might be us

ISSN:0272-8397    

DOI:10.1002/pc.750140103

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractBioabsorbable composites were fabricated from poly(D, L‐lactide‐urethane) matrix reinforced with poly(glycolic acid) (DEXON) surgical mesh. The crosslinked polyurethane matrix was formed from the reaction of ethy1–2, 6‐diisocyanatohexanoate and poly (D, L‐lactide) triol, initiated from glycerol; the ultimate degradation products of this matrix, L‐lysine, lactic acid, glycerol, and CO2, are all nontoxic, naturally occurring metabolites. The composites were fabricated by two processing methods, with the final composite structures displaying very different physical properties. Composites fabricated by vacuum bag molding displayed tensile strength and modulus of 66 MPa and 468 MPa, respectively, with total elongation of 39%. Composites fabricated by the same method, but whose final cure included 24 h at 5000 psi, displayed tensile strength and modulus of 86 MPa and 3.4 Gpa, respectively, with total elongation of 18%, suggesting a more fully developed matrix/fiber interphase and a reduction in microvoids, which lead to lower force failures. As poly(D, L‐lactide) prepolymer molecular weights decreased, tensile strengths and glass transition temperatures of the polyurethane networks increased. These trends were attributed to increased hydrogen bonding with an increased crosslink density. The composites were sensitive to cyclic loading, regardless of the processing technique, suggesting an inefficient transfer of energy from the matrix into the load‐bearing fibers. This weakness was confirmed by SEM microscopy, which revelaed a gap at the fiber/matridx interface of an unfatigued composite sample, poly(D, L‐lactide‐urethane) matrix composites were found to be unique since they can be custom shaped when heated above the glass transition of the matrix. DSC revelaed the glass transitions for the matrices of around 60°C. The composites were easily shaped above this temperature, yet remained rigid at bi

ISSN:0272-8397    

DOI:10.1002/pc.750140104

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractGlass fiber reinforced thermoplastic matrix sheet composites of polypropylene and poly(ethylene terephalate) were produced in a two‐stage pilot scale impregnation and consolidation process. The first stage consisted of preparing wet‐formed mats of long, discontinuous fibers and polymer powder on an inclined wire paper‐making machine. The second stage consisted of consolidating approximately 15 wet‐formed mats into a solid composite laminate by the application of heat and pressure in a compression press. The resulting composites had a nominal glass content of 26 wt% (∼12 vol %). Flexural strengths as high as 108 MPa for polyproplene composites and 132 MPa for poly(ethylene terephthalate) composites were measured on specimens cut from stamped parts. The flexural modulus of the polypropylene compsites reached 5.4 Gpa, while the modulus of the stiffest poly(ethylene terephthalate) composite was 8.1 Gpa. The impact properties of the composites were equally good. Polyproplene compsites absorbed up to 62 J/cm during an instrumented falling dart impact test, while poly(ethylene terephthalate) composites absorbed as much as 32 J/cm during the

ISSN:0272-8397    

DOI:10.1002/pc.750140105

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractA new technique was used to fabricate performed glass fiber/polypropylene GMTs. The method utilizes thermoplastic powder and fiber roving in a spray‐up procedure in which a porous perform in fabricated, heated and molded. The objective was to compare the properties of various preformed GMT composition with two commercial GMTs and to relate the mechanical properties to the microstructure of the materials. Preformed GMTs were fabricated with various fiber lengths and with or without a fiber/matrix adhesion promotor. Processing observation, microstructure, tensile creep modulus, and tensile strength of these preformed GMTs are reported. Fiber length and the addition of a fiber/matrix adhesion promotor had generally little effect on the modulus and strength of the preformed GMT. Comparisons with two structurally different commercial GMTs also showed negligible effects on modulus and strength. The major reason for this is suggested to be the inhomogeneities of the materials. The mechanical properties are controlled by local inhomogeneities rather than by the general microstructure of the material. These inhomogeneities arise from the fiber arrangement in the semi‐finished sheet or perform. Since the microstructure of preformed GMT can be controlled, this material is well suited for future studies on the effect of better fiber dispers

ISSN:0272-8397    

DOI:10.1002/pc.750140106

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study relates the formability of thermoplastic poly(ethersulfone) HTA composites to thermooxidative history and rehological behavior. HTA/IM8 graphite fiber performs were prepared under various temperature, time, and environmental (unbagged and vacuum‐bagged) conditions, then consolidated into finished laminates under identical conditions. X‐ray photoelectron spectroscopy and pyrolysis/gas chromatography/mass spectrometry were used to assess chemical degradation, and dynamic mechanical analysis (DMA) was used to evaluateTgand rheological behavior in the finished laminates. All performing conditions resulted in some degradation of the HTA matrix, the presence of air being especially detrimental. The nature of this degradation is discussed and related to changes inTg., melt viscosity of the matrix resin, and the extent of consolidation. A new DMA approach to evaluating degree of consolidation is developed and shown to offer considerable promise for quantitative assessment and ranking of composi

ISSN:0272-8397    

DOI:10.1002/pc.750140107

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractThe flow of fiber‐reinforced composite materials in a plate‐rib type mold geometry during compression molding was investigated using a series of sheet molding compounds (SMC). Material anisotropy in relation to the amount and the length of reinforcing fibers was analyzed. The influence of the interfacial friction between SMC charge and the mold surface on the flow and sink mark formation was also examined. The results were explained qualitatively by computer simulat

ISSN:0272-8397    

DOI:10.1002/pc.750140108

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractA thin film method is developed for the fabrication of an amorphous metallic ribbon/PP (polypropylene) matrix composite system. The interfacial shear strength of composites fabricated with thin film is 0.52 ± 0.09 MPa (process B), which is comparable to that of the sandwich method of composite fabrication reported recently. The optical micrographs of the interfacial zone appear to be defect free and there are no visible voids, cracks, or air entrapment during fabrication. This qualitative analysis of the ribbon/matrix interface suggests that thin film can provide a better interfacial bond, a result which is supported by the results of pullouts tests. The composite fabrication time using the thin film method is short, and this method therefore has the potential to produce composites at a high volume fraction of ribbon reinforcements as compared to the sandwich method

ISSN:0272-8397    

DOI:10.1002/pc.750140109

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of PVA (polyvinyl alcohol) concentration and the immersion time of the Fe40Ni40B20ribbon was studied in terms of interfacial shear strength. First, the PVA concentration was constant at 9 wt% while the immersion time of the ribbon is the solution was changed form 20 to 200 h. Second., the immersion time was constant at 144 h while the concentration of the PVA was changed form 1 to 12 wt%. The interfacial shear strength improved only slightly by increasing the immersion time from 20 h (0.55 ± 0.09 MPa) to 100 h (0.86 ± 0.12 MPa). The interfacial shear strength increased sharply form 0.86 ± 0.12 MPa at 100 h of immersion time to 3.02 ± 0.66 MPa at 144 h of immersion time. After 144 h of immersion, the interfacial shear strength almost leveled off (2.97 ± 0.26 MPa) at 200 h of immersion. The surface of the polypropylene (PP) after pullout and just before the ribbon fracture was studied with a scanning electron microscope (SEM). The low interfacial shear strength of composites immersed for less than 100 h is related ot the insufficient coating on the ribbon and a lack of the well developed interfacial zone. This is manifested by the presence of circumferential bands and impression from rough marking of the ribbon contact side left on the PP surface. The presence of parabolic markings and growth of spherulites on the PP surface may explain the higher interfacial shear strength observed at longer immersion times in the PVA, which suggests the existence of the well developed interfacial zone between ribbon and the PP matrix. The effect of PVA concentration on interfacial shear strength is almost similar to the effect of immersion

ISSN:0272-8397    

DOI:10.1002/pc.750140110

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY

摘要:

AbstractNon‐isothermal mold filing and curing experiments of liquid composite molding were carried out in this work. To compare the experimental results with a previously developed numerical simulation model, measurements of volumetric heat transfer coefficient between the resin and the fiber, and characterization of resin kinetics and rheological changes were also conducted. Combined with the previously measured fiber perform permeability, the numerical model provided a good prediction of temperature profiles during molding for a polyurethane/glass fiber composit

ISSN:0272-8397    

DOI:10.1002/pc.750140111

出版商:Society of Plastics Engineers    

年代:1993

数据来源: WILEY